The mobile communication system has been developed for the user to communicate on the move. With the rapid advance of technologies, the mobile communication system has evolved to the level capable of providing high speed data communication service as well as voice telephony service. Recently, as one of the next generation mobile communication system, Long Term Evolution (LTE)/LTE-Advanced (LTE-A) is on the standardization by the 3rd Generation Partnership Project (3GPP). LTE is a technology designed to provide high speed packet-based communication of up to 100 Mbps and aims at commercial deployment around 2010/2011. LTE-A has been evolved from LTE to improve data with the adoption of various novel technologies.
In the case of such a mobile communication system, a network may be implemented with a plurality of cells using the same frequency but various in size. For example, a plurality of macro, pico, and femto cells operating on the same frequency band may coexist. The macro, pico, and femto cells may be differentiated by size: a macro cell is the cell large relatively in size and pico and femto cells are (very) small relatively in size.
In the case that a network is configured as above, the terminal may access a macro, pico, or femto cell. If the radio channel measured by the terminal fulfils a cell (re)selection condition, it performs cell (re)selection process. At this time, a high speed terminal (high-mobility User Equipment (UE)) may attempt cell (re)selection operation frequently. That is, in the case that the high-mobility UE (re)selects the pico or femto cell, it is likely to repeat cell (re)selection immediately due to the high mobility, resulting in inefficient power consumption of UE.